Dubbed "Gmail in personal search results," the new service is available now in a field trial for users who sign up on Google's Search Experiments website. Although Google says it won't be able to accommodate everyone, I was able to sign up and activate the feature in just a few minutes.

Google doesn't search your Gmail account every time you run a Web search. Instead, it offers to show Gmail results for certain types of queries, such as band names and locations. When Google has Gmail results to show, a box on the right-hand side of the screen says who the messages are from. You can then expand this box to see snippets of each message, and from there you can jump into Gmail to read the whole thing.

A couple types of queries will show Gmail information automatically: When you search Google for an upcoming flight that you've booked, flight times and other information appear alongside standard search results. When you search for a person in your contacts list, you may see contact information plus a list of recent e-mails. (This worked for me when I entered the name of my editor into Google search, but not the name of my wife.)

Gmail integration could become useful if Google expands it to show a broader range of search results. But the company will have to tread carefully in rolling this feature out. E-mail is inherently private, and if someone's borrowing your computer to search the Web, they could come across messages that they otherwise wouldn't see without visiting Gmail proper.

As The Next Web reports, Google sees this feature as part of a bigger effort to offer "Universal Search." It's in the same vein as the inclusion of Google+ data alongside standard Web search results, and to some extent, the new Google Now service for Android. The goal, I think, is to have a single search function for finding everything you might need.

It's an exciting concept, and I can imagine Google Now eventually culling information from Gmail, Google+ and other sources to become a better virtual assistant. The trick is to roll out these features in a way that doesn't invade anyone's privacy. More field trials like this, and fewer things that require an opt-out, please.